1. Field of the Invention
The present invention relates to an image forming apparatus having a plurality of removable developing devices.
2. Description of the Relates Arts
There have been numerous proposals in recent years for multicolor copy machines, that is, copy machines using electrophotographic methods have been provided with multiple developing devices which could be selectably operated to produce copies in specified colors. In the aforesaid type of multicolor copy machine, there is an inherent problem of color mixing by the toner accommodated in the developing devices. This problem is an unavoidable problem associated with electrophotographic methods.
When color mixing occurs, particularly when, for example, black or other color toner is introduced into a developing device accommodating white toner, the white toner is contaminated so that the white toner darkens and a pure white toner color is unavailable. Thus, when a white developing device is installed, said device is installed so as to be disposed above the installation position of the color developing devices, thereby preventing as far as possible the introduction of toner overflowing from a color developing device into the white developing device and contamination of the white developing device by toner from a color developing device via the rotation of the photoconductive drum.
In image forming apparatus that can accommodate the installation of multiple developing devices, however, user error may lead to the image forming apparatus being operated after the operator mistakenly installs a color developing device at a position above the white developing device.